Re: Backward compatibility of next beta

[Arrigo Marchiori]

Hello,

On Tue, Jan 28, 2020 at 03:45:19PM -0500, Derek Atkins wrote:

> Hi,
> 
> Frank Crawford <address@hidden> writes:
> 
> > (Sorry about the previous formatting I'm resending this formatted
> > correctly)
> >
> > Rigo,
> >
> > It depends on what you mean by compatible.
> >
> > Python3 version of rdiff-backup is not interoperable for remote
> > operations with python2 rdiff-backup, so v2.0.0 will not work with
> > v1.2.8 or v1.3.3.  This is a python3 vs python2 issue and could not be
> > fixed without major changes to both versions.
> 
> So just to be clear, the version of "rdiff-backup --server" must match
> the other version?  Right now I have a backup server that basically
> runs:
> 
> rdiff-backup <excludelist> hostname_backup::<dir> <targetdir>/hostname
> 
> Where "hostname_backup" is an SSH configuration, and it then uses SSH to
> connect to "hostname" where it creates and mounts an LVM snapshot and
> then runs "rdiff-backup --server --restrict-read-only /mnt/snap"
> 
> Having said all this, what you're saying is that once ANY of my target
> hosts get upgraded to a point where they can only run
> rdiff-backup-2.0.0, then I must upgrade ALL most hosts (and backup
> server) to be running rdiff-backup-2.0.0?
> 
> IMHO, that is a VERY VERY BAD THING.
> 
> > However, the backup archives that are created are compatible, so if you
> > did a backup with an older version, you can continue using it with no
> > issues.
> >
> > In fact, while this isn't in the planned distribution, there is some
> > comment by someone who has written a wrapper that invokes either a
> > python2 or python3 version, depending on what it is talking to.  Of
> > course the python2 version is either v1.2.8 or v1.3.3, not v2.0.0.
> 
> I think this is extremely important to get into the release in order to
> handle the use case stated above!  I certainly can't believe that I am
> the only person who uses rdiff-backup this way to back up remote
> machines.

Maybe you could find a solution by using the --remote-schema
parameter? If I understood correctly, it should allow you to keep two
versions of rdiff-backup side-by-side, rather than upgrading the
program at ``system-level''.

I cannot try this, but I would suggest:

 1- on the client _and_ server, install the new version in ~/rdiff-backup-2
 2- run the version 2 client with the parameter:
      --remote-schema 'ssh -C %s ~/rdiff-backup-2/rdiff-backup --server'
    
I hope this helps,
-- 
rigo

http://rigo.altervista.org